1. Field of the Invention
This invention relates to hand and power tools, and specifically to tools adapted for use with interchangeable tool bits. More particularly, the invention relates to a simple, strong, and durable driver for such tool bits.
2. Background of the Invention
Tools, whether driven by hand or machine, are used in a vast array of circumstances and environments. Tools are used by the individual consumer for occasional jobs around the house and by professional technicians in commercial and industrial applications such as in repair shops and assembly lines.
For reasons including convenience and economy, many tools are designed to accept interchangeable tool bits such as screwdriver heads and sockets. With this design, a single handle can be used to drive, for example, a slotted Phillips type screwdriver or, with a simple change of bits, a regular blade head. In the case of socket wrenches, a single wrench handle, turned by hand or powered by, for example, compressed air, can be used to tighten or loosen different sized bolts or nuts by selecting the correctly sized socket.
In the case of socket wrenches, it has become the industry standard to offer a limited range of handles or drivers for the sockets. Each handle or driver has a single drive portion, or simply drive, for engaging a set of sockets. The most common sizes for tool drivers for socket wrenches are one-quarter inch (xc2xcxe2x80x3, or 6.35 mm), three-eighths inch (xe2x85x9cxe2x80x3, or 9.53 mm), and one-half inch (xc2xdxe2x80x3, or 12.7 mm).
The tool driver is typically a square-shaped extension from the handle, the length of the side of the square giving the tool its size designation. A common feature of most tool drivers is the provision of a detent on at least one side of the square. The purpose of the detent is to increase the friction of the fit between the tool driver and the tool bit, and may be used to help retain the bit on the driver. The detent may be a simple projection, but is more often in the form of a small metal sphere or ball bearing. The ball bearing partially protrudes through an opening in the driver. The detent is often spring biased outwardly of the driver, and the bias may be releasable to allow a tool bit to easily slide on or off the driver.
The tool driver is operatively connected to a torquing mechanism. In its simplest form for a hand tool, the torquing mechanism may consist only of a solid connection to a handle, the torque needed to turn the bolt being provided by the user. The common ratchet wrench allows a user to manipulate the handle in a reciprocal motion while applying torque in only one direction. Power and machine tools may have more complicated torquing mechanisms.
In a given set of sockets designed for use with one of these drivers, each socket will have an opening complementary in size and shape to the size and shape of the tool driver. The opening may also have an internal ridge or trough to engage a detent on the driver. The tool driver engages the opening, and applying torque to the driver in turn provides torque to the socket. The socket has another opening designed to engage a nut or bolt of given size. This second opening will vary from socket to socket within a set to allow an operator to work with different sized fasteners.
It is frequently necessary, especially in operations such as inspection and repair, to tighten or remove several bolts of varying sizes. While the varying size of sockets in a set make it possible sometimes to simply switch to another socket in the same set, it is often necessary to switch to a socket from another set.
The simplest solution for this need is to maintain handles and/or torquing mechanisms for each standard set. In most commercial and industrial applications, however, a fairly wide variety of handle sizes and types, both hand- and power-driven, must be available to each technician. Requiring one of each size handle to be available to each technician can be expensive, while arranging for technicians to share handles often causes delay in one project while another is being accomplished. Moreover, to switch handles, a technician must frequently leave the work station to obtain the needed handle. While each such action may take only a short while, many of these occurring during a shift creates a significant amount of downtime.
Another attempted solution is to provide drive adapters. A typical drive adaptor has a shaft constructed such that it will engage the tool driver of a wrench, for example, at one end. The other end is shaped as a tool driver and dimensioned either larger or smaller than the driver of the wrench so that it can be used with the sockets of a different sized set. While perhaps not as expensive as a full handle, a need for adapters still requires purchase of additional parts.
An additional problem with the use of adapters is the extra length inevitably added to the tool driver. First, especially where a workspace is particularly confined, the additional length may make it difficult or impossible to properly manipulate the tool. Also, the tightening or loosening operation is less efficient. While there is in theory no loss of torque by adding a length at right angles to the direction of torque, as a practical matter, there is. Wear and tear on the adaptor and/or the bolt or workpiece resulting in a less-than-perfect fit result in the torque being applied out of the plane of the bolt, which greatly decreases the efficiency of the tool. The improper fit itself will also contribute greatly to the wear on both the workpiece and the tool.
Several alternatives have been proposed to eliminate the need for adapters and to provide different tool driver sizes in a single tool. These alternatives involve providing sliding or telescoping arrangements for exposing different sized drivers for use with different standard sets. Incorporating such mechanisms into handles or power tools that must, to be competitive and useful, also incorporate reversible ratcheting mechanisms, releasable detents, and the like greatly increases the complexity and hence cost of such tools. Any contaminants such as dirt, grease, or metal filings pose the potential for making the tool inoperable. The complexity of the tool will make repair difficult, and replacement expensive. Finally, as the tool becomes more complex, the amount of force that can be exerted through the tool, and the expected life of the tool, decrease.
There is thus needed in this art an alternative tool driver that overcomes and avoids the foregoing problems.
It is an object of the invention to provide a simple, strong, and durable tool driver.
It is also an object of the invention to provide an inexpensive tool driver capable of use with at least two different sets of standard tool bits.
It is a further object of the invention to provide a tool driver adapted to fit at least two different sets of standard tool bits without the need for complex structures or manufacturing techniques.
It is moreover an object of the invention to provide such a tool driver having releasable detents for securing on the driver a tool bit from either of two standard sets.
It is another object of this invention to provide a tool driver capable of driving tool bits from at least two different standard sets, and capable of being used with existing torquing mechanisms and handles.
These and other objects are achieved by providing a tool driver for use with a torquing mechanism, having a shaft of predetermined length, the shaft having a first end and a second end; the first end being operatively connected to the torquing mechanism; the second end having a first drive terminal to the second end and a second drive adjacent the first drive; the first drive having a first cross-sectional dimension whereby it can releasably engage any one of a first set of standard tool bits; and the second drive having a second cross-sectional dimension whereby it can releasably engage any one of a second set of standard tool bits, the second cross-section dimension being different from the first cross-sectional dimension. These and other objects of the invention are also provided by such a tool driver wherein a releasable detent is provided in each drive to aid in releasably engaging the tool bits.